Method and apparatus for transmitting/receiving data in mobile communication system

ABSTRACT

The present invention relates to a method and an apparatus for transmitting/receiving data, and a method for a user equipment transmitting data, according to one embodiment of the present invention, comprises: a step of determining conditions for determining whether a condition for transmitting short data is satisfied, when data to be transmitted is generated; and a step of including the data to be transmitted in a radio resource control (RRC) connection setup completion message and transmitting same, when the condition for transmitting the short data is satisfied. According to one embodiment of the present invention, the problem of network overload can be prevented by reducing signaling overhead when processing small packets, which are generated intermittently, in the mobile communication system, and an apparatus and a method for enhancing battery performance in the user equipment can be effectively provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 15/483,979,filed Apr. 10, 2017, which is a continuation of application Ser. No.14/111,530, which is the National Stage of International Application No.PCT/KR2012/002726, filed Apr. 10, 2012, now U.S. Pat. No. 9,622,164,which claims the benefit of Provisional Application No. 61/473,966,filed Apr. 11, 2011, this disclosures of which are incorporated hereinby reference into the present disclosure as if fully set forth herein.

BACKGROUND 1. Field

The present disclosure relates to a method and apparatus fortransmitting/receiving data in a mobile communication system.

2. Description of Related Art

The mobile communication system has been developed for the user tocommunicate on the move. With the rapid advance of technologies, themobile communication system has evolved to the level capable ofproviding high speed data communication service as well as voicetelephony service.

Recently, as one of the next generation mobile communication system,Long Term Evolution (LTE) is on the standardization by the 3^(rd)Generation Partnership Project (3GPP). LTE is a technology designed toprovide high speed packet-based communication at a data rate of up to100 Mbps and aims at commercial deployment around 2010 timeframe.

With the commercialization of various packet services, it is frequentthat small size packets occur sporadically. In the general mobilecommunication systems including LTE, it is inevitable to establish asignaling connection and data bearer to transmit a packet even when thepacket is so small. This causes frequent control data exchange and, if aplurality of terminals try to establish connections for small size datatransmission, this causes significant network overload and degradesbattery performances of the terminals.

SUMMARY

The present disclosure has been proposed to solve to above problem andaims to provide a method and apparatus for processing small andsporadically-occurring packets efficiently.

In accordance with an aspect of the present disclosure, a datatransmission method of a terminal includes determining, when a data tobe transmitted occurs, whether a short data transfer condition isfulfilled and transmitting, when the short data transfer condition isfulfilled, a Radio Resource Control (RRC) setup complete messageincluding the data.

In accordance with another aspect of the present disclosure, a terminalfor transmitting data includes a controller which determines, when adata to be transmitted occurs, whether a short data transfer conditionis fulfilled and a transceiver which transmits, when the short datatransfer condition is fulfilled, a Radio Resource Control (RRC) setupcomplete message including the data.

The data transmission/reception method of the present disclosureprovides an apparatus and method for transmitting/receiving data in amobile communication system that is capable of processing small andsporadically-occurring packets efficiently to reduce network overloadand improve battery performance of the terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating network architecture of an LTE systemto which the present disclosure is applied,

FIG. 2 is a diagram illustrating a protocol stack of the LTE system towhich the present invention is applied,

FIG. 3 is a diagram illustrating a procedure for UE 135 to establish aconnection to a network for data communication,

FIG. 4 is a diagram illustrating embodiment 1 of the present disclosure,

FIG. 5 is a flowchart illustrating the data transfer procedure,

FIG. 6 is a diagram illustrating the normal security 1 process and themodified security 1 process,

FIG. 7 is a diagram illustrating message formats of embodiment 1 of thepresent disclosure,

FIG. 8 is a diagram illustrating integrity protection,

FIG. 9 is a diagram illustrating ciphering/deciphering,

FIG. 10 is a drawing illustrating UE device operation of embodiment 1,

FIG. 11 is a drawing illustrating MME 125 device operation of embodiment1,

FIG. 12 is a drawing illustrating another modified security 1 procedure,

FIG. 13 is a drawing illustrating the UE operation to which anothermodified security 1 procedure is applied,

FIG. 14 is a drawing illustrating entire operation of processing MobileTerminated call of embodiment 1,

FIG. 15 is a drawing illustrating entire operation of embodiment 2,

FIG. 16 is a diagram illustrating a data format of the special DRB,

FIG. 17 is a drawing illustrating a UE operation of embodiment 2,

FIG. 18 is a diagram illustrating the UE device according to anembodiment of the present disclosure, and

FIG. 19 is a diagram illustrating the network device according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

Detailed description of well-known functions and structures incorporatedherein may be omitted to avoid obscuring the subject matter of thepresent invention. Exemplary embodiments of the present invention aredescribed with reference to the accompanying drawings in detail.

The present disclosure relates to a method and apparatus for processingdata small in size and occurring sporadically. Prior to explaining thepresent invention, brief description is made of the LTE system andcarrier aggregation.

FIG. 1 is a diagram illustrating network architecture of an LTE systemto which the present disclosure is applied.

As shown in FIG. 1, the radio access network of the LTE system includesevolved Node Bs (eNBs) 105, 110, 115, and 120, a Mobility ManagementEntity (MME) 125, and a Serving-Gateway (S-GW) 130. The User Equipment(hereinafter, referred to as UE) 135 connects to an external network viaeNBs 105, 110, 115, and 120 and the S-GW 130.

The eNBs 105, 110, 115, and 120 correspond to the legacy node B of UMTSsystem. The eNB 105 establishes a radio channel with the UE 135 and isresponsible for complex functions as compared to the legacy node B. Inthe LTE system, all the user traffic including real time services suchas Voice over Internet Protocol (VoIP) are provided through a sharedchannel and thus there is a need of a device which is located in the eNBto schedule data based on the state information such as UE bufferconditions, power headroom state, and channel state. Typically, one eNBcontrols a plurality of cells. In order to secure the data rate of up to100 Mbps, the LTE system adopts Orthogonal Frequency DivisionMultiplexing (OFDM) as a radio access technology. Also, the LTE systemadopts Adaptive Modulation and Coding (AMC) to determine the modulationscheme and channel coding rate in adaptation to the channel condition ofthe UE. The S-GW 130 is an entity to provide data bearers so as toestablish and release data bearers under the control of the MME 125. MME125 is responsible for various control functions and connected to aplurality of eNBs 105, 110, 115, and 120.

FIG. 2 is a diagram illustrating a protocol stack of the LTE system towhich the present invention is applied.

Referring to FIG. 2, the protocol stack of the LTE system includesPacket Data Convergence Protocol (PDCP) 205 and 240, Radio Link Control(RLC) 210 and 235, Medium Access Control (MAC) 215 and 230, and Physical(PHY) 220 and 225. The PDCP 205 and 240 is responsible for IP headercompression/decompression, ciphering, and Integrity Protection, and theRRC 210 and 235 is responsible for reconstructing the PDCP Protocol DataUnit (PDU) into appropriate size. The MAC 215 and 230 is responsible forestablishing connection to a plurality of RLC entities so as tomultiplex the RLC PDUs into MAC PDUs and demultiplex the MAC PDUs intoRLC PDUs. The PHY 220 and 225 performs channel coding on the MAC PDU andmodulates the MAC PDU into OFDM symbols to transmit over radio channelor performs demodulating and channel-decoding on the received OFDMsymbols and delivers the decoded data to the higher layer.

FIG. 3 is a diagram illustrating a procedure for UE 135 to establish aconnection to a network for data communication.

If data occurs at the UE 135 in idle mode, the UE 130 performs RRCCONNECTION ESTABLISHMENT procedure with the eNB 105. The UE 135 acquiresuplink transmission synchronization with the eNB 105 through a randomaccess procedure and sends the eNB 105 an RRC CONNECTION REQUEST messageat operation 305. This message includes the identifier of the UE 135 andthe reason for connection establishment. The eNB 105 sends the UE 135 anRRC CONNECTION SETUP message for establishing the RRC connection atoperation 310. This message includes RRC connection configurationinformation. The RRC connection is also called Signaling Radio Bearer(SRB) and used for exchanging RRC messages as control messages betweenthe UE 135 and the eNB 105.

After the RRC connection establishment, the UE 135 sends the eNB 105 anRRC CONNECTION SETUP COMPLETE message at operation 315. This messageincludes a SERVICE REQUEST message requesting the MME 125 for bear setupfor a certain service. The eNB 105 sends the MME the SERVICE REQUESTmessage included in the RRC CONNECTION SETUP COMPLETE message atoperation 320, and the MME 125 determines whether to provide the servicerequested by the UE 135. If it is determined to provide the servicerequested by the UE 135, the MME 125 sends the eNB 105 an INITIALCONTEXT SETUP REQUEST message at operation 325. This message includesQoS information to be applied Data Radio Bearer (DRB) establishment,security information to be applied to DRB (e.g. security key), SecurityAlgorithm, etc.

The eNB 105 sends the UE 135 a SECURITY MODE COMMAND message atoperation 330 and receives a SECURITY MODE COMPLETE message from the UE135 at operation 335 to configure security. If the securityconfiguration has completed, the eNB 105 sends the UE 135 an RRCCONNECTION RECONFIGURATION message at operation 340. This messageincludes the configuration information on the DRB for processing userdata, and the UE 135 configures DRB based on this information and sendsthe eNB 105 an RRC CONNECTION RECONFIGURATION COMPLETE message atoperation 345.

Once the DRB configuration with the UE 135 has completed, the eNB 105sends the MME 125 an INITIAL CONTEXT SETUP COMPLETE message at operation350 and, upon receipt of this message, the MME 125 transmits an S1BEARER SETUP message to the S-GW 130 and receives an S1 BEARER SETUPRESPONSE message from the S-GW 130. The S1 BEARER is the connection fordata transmission which is established between the S-GW 130 and the eNB105 and mapped to the DRB 1 by 1. Once the above procedure hascompleted, the UE 135 starts data communication via the eNB 105 and theS-GW 130 at operations 365 and 370.

Basically, the UE 135 and the network maintain two types of securityconfigurations. Assuming that the security between the UE 135 and theMME 125 is security 1 and the security between the UE 135 and the UE 105is security 2, the securities are characterized as follows.

Security 1: This is the security provided for the control messagebetween the UE 135 and the MME 125 (hereinafter, the control messagebetween the UE and the MME 125 is referred to as NAS message) based on apredetermined security key, security algorithm, and COUNT. The security1 is maintained even when the UE 135 which has initially connected thenetwork already enters the idle mode. The security 1 provides integrityprotection and ciphering. The integrity protection is applied to all NASmessages with the exception of the initial connection message, and theciphering is applied after the first DRB establishment to the UE 135.The UE 135 transmits the service request message including theinformation indicating the security key applied, and the MME 125performs integrity check using the above information and a sequencenumber of the service request. If the integrity check is verified,subsequent NAS messages are ciphered. The COUNT is a variable increasingmonotonically by packet and derived from NAS sequence number.Hereinafter, the variable COUNT of security 1 is referred to as COUNT1.

Security 2: This is the security provided for data exchange between theUE 135 and the eNB 105 using other security key, security algorithm, andCOUNT. The security 2 is applied after the UE establishes the RRCconnection and exchanges security mode command/complete messages withthe eNB 105 and performed by PDCP layer. The security key and algorithminformation are determined in the security mode configuration procedure.The COUNT is a variable increasing monotonically by packet and derivedfrom the PDCP sequence number. Hereinafter, the variable COUNT ofsecurity 2 is referred to as COUNT2.

The procedure of FIG. 3 may be divided into three processes of RRCconnection establishment (305, 310 and 315), security 2 configuration(330 and 335), and DRB configuration (340 and 345). Such processes maybe performed with no problems in the normal data transmission but, if afew small size packets are transmitted after establishing connection,performing all of the processes increases signaling overheadsignificantly.

In order to solve the above problem, the present disclosure defines anew data transmission procedure appropriate for small size sporadicpacket transmission (hereinafter, referred to as short data transferprocedure).

If new data occurs in the idle mode UE (UE with no RRC connection atoperation 405, the UE 135 determines whether the new data fulfills theshort data transfer condition at operation 410 and performs, if the datadoes not fulfills the condition (i.e. if the legacy data transferprocedure is preferable), performs the data transfer procedure 1 atoperation 415 and, otherwise the short data transfer procedure ispreferable, the data transfer procedure 2 at operation 420.

The data transfer procedure 1 denotes the procedure depicted in FIG. 3.The data transfer procedure 2 is characterized as follows and describedwith reference to FIG. 5.

-   -   Apply security 1    -   transmit IP packet using SRB and control connection

There may be short data transfer use conditions as follows.

[short data transfer procedure-invoke condition 1]

Data occur on predetermined EPS bearer (or predetermined service) of RRCidle and ECM-IDLE terminal 135. The EPS bearer is selected by thenetwork in the EPS bearer setup procedure between the eNB 135 and thenetwork and notified to the eNB 135. For example, the EPS bearer for theinstant messaging service may be configured to invoke the short datatransfer procedure.

[short data transfer procedure-invoke condition 2]

A packet smaller than a predetermined threshold value occurs in the RRCidle and ECM-IDLE UE 135. The packet size is the size before thePDCP/RLC/MAC header is added.

[short data transfer procedure-invoke condition 3]

A packet occurs on a certain EPS bearer of the RRC idle and ECM-IDLE UE135, and a number of packets occurred on the EPS bearer in apredetermined recent time duration is equal to or less than apredetermined value. For example, if a new packet occurs on the EPSbearer of the RRC idle and ECM-IDLE UE 135 on which the total downlinkand uplink packets occurred within recent 10 minutes is equal to or lessthan 5, this invokes the short data transfer procedure.

A packet occurs in the RRC idle and ECM-IDLE UE 135, and a number ofpackets occurred in the UE 135 within a predetermined recent timeduration is equal to or less than a predetermined value. For example, ifa packet occurs in the RRC idle and ECM-IDLE UE 135 in which the totaldownlink and uplink packets occurred within recent 10 minutes is equalto or less than 5, this invokes the short data transfer procedure.

[short data transfer procedure-invoke condition 4]

A packet occurs on a certain EPS bearer of the RRC idle and ECM-IDLE UE135 and a number of packets occurred in the most recent RRC connectionstate or most recent active state on the EPS bearer is equal to or lessthan a predetermined value.

A description is made of ECM-IDLE state hereinafter.

ECM-IDLE State

When there is not NAS signaling connection between the UE and thenetwork, the UE is in the ECM-IDLE state. The MME 125 stores UE contextsuch as security context and allowed QoS profile. In the ECM-IDLE state,the UE performs cell selection/reselection and Public Land MobileNetwork (PLMN). The UE context for the UE in ECM-IDLE state does notexist in E-UTRAN. There is no S1_MME and S1_U connection for the UE inthe ECM-IDLE state. If the current Tracking Area (TA) does not exists inthe TA list received from the network, the UE has to update TA tomaintain registration, allow the MME 125 to page the UE, and performservice request procedure to reply in response to the paging from theMME 125 and has to perform service request procedure for establishingradio bearers in transmitting uplink user data.

A description is made of RRC idle state hereinafter.

If a RRC connection is established, the UE is in the RRC_CONNECTEDstate. In other case, i.e. if not RRC connection is established, the UEis in the RRC_IDLE state. The UE applies UE-controlled mobility,monitors paging to detect incoming call and change in systeminformation, performs neighbor cell measurement and cell (re)selection,and acquire system information.

A description is made of the EPS bearer hereinafter.

The EPS bearer is single level for controlling bearer level QoS controlin the EPC/E-UTRAN. That is, all the traffics mapped to the same EPS arereceived with the same bearer level packet forwarding process (e.g.scheduling policy, queue management policy, rate shaping policy, and RLCconfiguration). Providing other bearer level packet forwarding policiesrequire separate EPS bearers.

Each EPS bearer (GBR and Non-GBR) is associated with the followingbearer level QoS parameters.

-   -   QoS Class Identifier (QCI);    -   Allocation and Retention Priority (ARP).

QCI is a scalar quantity used as a reference value for accessingnode-specific parameters controlling bearer level packet forwardingprocess (scheduling weights, admission thresholds, queue managementthreshold value, link layer protocol configuration, etc.) andpreconfigured by the operator of the access node such as eNB.

ARP has to include information on the priority level (scalar),preemption capability flag, and preemption vulnerability flag. The mainpurpose of the ARP is to determine whether to accept or reject thebearer establishment/reconfiguration request depending on the resourcerestriction.

FIG. 5 is a flowchart illustrating the data transfer procedure 2.

A short data occurs in the UE 105 at operation 505. The RRC of the UE105 initiates the RRC Connection Setup procedure with a ‘short datatransfer’ reason value. An indicator indicating that the ‘short datatransfer’ procedure is required may be included in the RRC connectionsetup complete message at operation 515. It is not that all the datadepends on the data transfer procedure 2. The data transfer procedure 2is applied to only the predetermined EPS bearer (or when a predefinedcondition is fulfilled). Whether the EPS bearer is established for‘short data transfer’ is configured in the EPS

The eNB 150 sends an RRC connection setup message at operation 510. TheRRC connection setup message includes SRB 1 establishment information.The eNB 105 transmits an uplink grant for the UE 135 after the SRB1setup. Then the UE 135 may not initiate the random access procedure torequest for uplink grant for transmitting the RRC connection setupcomplete message for a predetermined duration.

The UE 135 sends the RRC connection setup complete message including IPpacket with a container (referred to as dedicatedNASInfo) for MME 125 atoperation 515. The RRC connection setup complete message may be carrierby a plurality of MAC PDUs. The first MAC PDU may include the MAC CEcarrying the Buffer Status Report (BSR) and Channel Quality Information(CQI). The CQI may include the following information.

CQI: CQI of the current cell. This information is derived from thereceived RSRP or RSRQ. This is mainly used for downlink scheduling.

Pathloss: pathloss of current cell's reference signal. This informationis derived from the downlink transmit power of the reference signal andRSRP. The downlink transmit power of the reference channel may beprovided in the system information. Since the eNB 105 knows the downlinktransmit power already, it may calculate the path loss with the RSRPother than pathloss.

Power headroom: information on the difference between the nominalmaximum UE output power and the power estimated for UL-SCH (i.e. MACPDU) transmission.

If the RRC connection setup complete message is received successfully,the eNB 105 sends the MME 125 the dedicatedNASInfo included in the RRCconnection setup complete message at operation 520.

The MME 125 deciphers the dedicatedNASInfo, de-multiplexes the IPpacket, and sends the S-GW 130 the IP packet at operation 525. The S-GW130 transmits the IP packet to the destination node based on the routinginformation included in the IP packet.

According to this embodiment, if the data transfer procedure 2 is used,the security 1 is applied even to the IP packet. That is, if the IPpacket is transmitted in the data transfer procedure 1, the security 2is applied thereto and, otherwise if the IP packet is transmitted in thedata transfer procedure 2, the security 1 is applied thereto.

As described above, the security 1 is used for providing security forthe NAS control message between the UE 135 and the eNB 105. In the caseof the short data, however, the security 1 is applied to the IP packetaccording to the present disclosure. In the normal security 1, the UE135 sends the MME 125 a service request message and, after a DRB isestablished in response thereto, ciphering is applied to the NASmessage. In the present disclosure, it is necessary to apply cipheringwithout establishment of any DRB and thus it is impossible to follow theabove procedure as it is. In the present disclosure, the application ofciphering starts from the NAS control message included in the RRCconnection setup complete message.

FIG. 6 is a diagram illustrating the normal security 1 process(operations 605 to 625) and the security 1 process for data transferprocedure 2 (operations 630 to 645). Operations 630 to 645 are theprocess performed in separation from operations 605 to 625 other thanfollowing operations 605 to 625. If the data transfer procedure 2 isused currently for NAS control message transmission, the UE applies amodified security 1 process and, otherwise if the data transferprocedure 2 is not used, applies the normal security 1 process. Forexample, in the security 1 process, the UE 135 applies the integrityprotection but not ciphering in transmitting the service request messageas the first control message to transition to the EMM-CONNECTED state atoperation 605. The service request message includes Key Set Identifier(KSI) as the information for identifying the security key used in thesecurity 1. Upon receipt of the above message, the MME 125 performsverification by referencing the Message Authentication Code (MAC)included in the message. If the message is verified, the MME 125activates the ciphering function of the security 1 and performs the UEcontext configuration procedure with the eNB 105 at operation 615. Ifthe ciphering function of the security 1 is activated, this means thatciphering is applied to the NAS message to be transmitted anddeciphering is applied to the NAS message received since then.

If the entire procedure for establishing the DRB with the UE 135 hascompleted, the eNB 150 sends the UE 135 a control message for commandingDRB configuration at operation 620. If the DRB is established initially,the UE 135 activates the ciphering function of the security 1 atoperation 625.

In the modified security 1 process, the UE 135 activates the cipheringfunction of the security 1 before transmitting the first control messagefor transitioning to the EMM-CONNECTED state at operation 630. That is,ciphering is applied to the first control message along with theintegrity protection. The UE 135 sends the MME 125 thepartially-ciphered first control message at operation 635, the MME 125,upon receipt of the control message, checks the MAC-I of the controlmessage to verify the control message at operation 640, and activates,if the message is verified, the ciphering function of the security 1 toperform deciphering on a predetermined part of the control message atoperation 645.

FIG. 7 is a diagram illustrating messages for use in transitioning tothe EMM-CONNECTED state. The first control message of the normalsecurity 1 procedure for transitioning to the EMM-CONNECTED state andthe first control message and subsequent message of the modifiedsecurity 1 process for transitioning to the EMM-CONNECTED state aredepicted in FIG. 7. The normal security 1 process is used in the datatransfer procedure 1 and the modified security 1 process is used in thedata transfer procedure 2.

In the case of using the normal security 1 process, the first NASmessage 740 may be the service request message. The NAS message includesthe normal control information such as protocol discriminator 705 andSecurity Header type 710. The protocol discriminator 705 is theinformation indicating the L3 protocol of the corresponding controlmessage, and the security header type 710 indicates whether theintegrity protection and/or ciphering is applied to the correspondingmessage.

The message 740 is protected by the integrity protection but notciphered. This means that the MAC 720 is applied to the correspondingmessage and its value is included in the message. The integrityprotection is described in detail as follows. The sender devicecalculates MAC by inputting the message 815 to which predetermined Key825, predetermined variables, and integrity protection to apredetermined device. The predetermined variables include COUNT 805,DIRECTION 810, BEARER 820, etc. The COUNT is a variable derived from theNAS sequence number, the DIRECTION is a variable determined depending onuplink/downlink, and the BEARER is a predetermined value. A descriptionis made of the COUNT in more detail hereinafter.

COUNT=0x00∥NAS OVERFLOW∥NAS SQN

When the 8 most left bits are all zero padding bits, the NAS OVERFLOW is16-bit value increasing at every time when the NAS SQN increases frommaximum value, and NAS SQN is a 8-bit sequence number included each NASmessage.

It is noted that the NAS sequence number is 5 bits other than 8 bits inthe messages 740 and 745. This is to transmit both the KSI and NASsequence number in 1 byte.

If a certain message is received, the receiver device calculates MAC byapplying the same algorithm, variables, and key to the message. If thecalculated MAC and the received MAC match, it is determined that thecorresponding message is verified.

In the data transfer procedure 2, the first message 745 fortransitioning to the EMM-connected state is protected entirely with theintegrity protection and ciphered partially. Unlike the message 740, themessage 745 includes the information 725 for identifying the type of thecorresponding message. This information is used for discriminatingbetween the messages 740 and 745 sharing the characteristic as the firstmessage for transitioning to the ECM-CONNECTED state.

FIG. 8 is a diagram illustrating algorithm of calculating MessageAuthentication Code (MAC). The MAC 730 is of being calculated for theentire message 745 or for a part remained after excluding the headerinformation related to the IP packet in the message 745. In more detail,the MAC 730 may be a value calculated with the input of a part excludingthe IP packet and related NAS header 735 and MAC 730 from the message745 to the message 815 or a value calculated by inputting a partexcluding the MAC 730 from the message 745 to the message 815. The IPpacket and related NAS header 735 is the concatenation of the IP packetto be transmitted by the UE 135 and the header of the NAS levelaccompanied with the packet. The header of the NAS level may include theinformation indicating that the payload contains IP packets.

FIG. 9 is a diagram illustrating the ciphering. The UE 135 appliesciphering to the IP packet and related NAS header 735 part but the otherpart in the message 745. The ciphering is completed by applying apredetermined operation (e.g. exclusive OR) to the KEYSTREAM BLOCKhaving the same length as the bit stream (PLAINTEXT 935) to which theciphering is applied. The KEYSTREAM BLOCK 930 is generated with apredetermined key, a predetermined algorithm, and predeterminedvariables including COUNT 905, BEARER 910, DIRECTION 915, and LENGTH920. The LENGTH is a variable indicating the length of the PLAINTEXT935/KEYSTREAM BLOCK 920. The deciphering is completed by applying apredetermined operation to the KEYSTREAM BLOCK 930 and CIPHERTEXT BLOCK940 generated with the same key, same algorithm, and same variables asthe ciphering.

When ciphering a part of the message 745, the UE 135 inputs the IPpacket and related NAS header 735 as the PLAINTEXT BLOCK 935, the lengthof the IP packet and the related NAS header 735 as the LENGTH 920, and avalue related to the sequence number of the message 745 as the COUNT,and uses the key derived from KSI as the ciphering key.

When deciphering the message 745, the MME 125 inputs the IP packet ofthe received message 745 and the related NAS header 735 as theCIPHERTEXT BLOCK 940 and a value related to the sequence number of themessage 745 as the COUNT and uses the key derived from the KSI as thedeciphering key.

The subsequent message 750 after transitioning to the EMM-connectedstate is identical with the message 745 with the exception that the KSIis not transmitted and 8-bit sequence number is used.

It is noted that the UE 135 and the MME 125 perform the integrityprotection after applying the ciphering. That is, the UE 135 calculatesthe MAC by inputting the ciphered IP packet and related NAS header 735as a part of the message, and the MME 125 calculates the MAC byinputting the IP packet and related NAS header 735 as the part of themessage too and, if the message is verified, performs deciphering on theIP packet and related NAS header 735. This is to perform the subsequentoperation using the information contained in the reliable message passedthe integrity check. In the case of applying the data transfer procedure1, security is applied to on PDCP, or the message 750 is processed, theciphering is performed after applying the integrity protection. This isbecause since the integrity check has been performed at the previousoperation already there is no need of verifying the reliability in unitof message at the sender device and the receiver device.

FIG. 10 is a flowchart illustrating the operations of the UE 135.

If the aforementioned short data transfer procedure invoke condition isfulfilled, the UE 135 starts the data transfer procedure 2 at operation1005.

The UE 135 transmits an RRC connection request message in the randomaccess procedure at operation 1010. This message includes the reason ofthe RRC connection setup procedure. The UE may inform that the messageis for the short data transfer procedure. The short data transferprocedure requirement may be indicated in the RRC connection completemessage.

If the RRC connection setup message is received at operation 1015, theUE 135 performs the following operations.

-   -   The UE 135 establishes an SRB 1 according to the information        received in the RRC connection setup message.    -   The UE 135 notifies the higher layer of the capability of the        short data transfer (manages EPS bearer data transfer). Then the        EPS bearer management entity sends the IP packet to the NAS        layer.    -   The NAS layer generates a message 745 by concatenating the        message type field, IP packet, and others. The NAS layer ciphers        the IP packet and related NAS header 735 part with the current        NAS security key and other variables. The NAS layer calculates        the MAC based on the current security key and other variables.        In normal case, it has to be noticed that the NAS ciphering is        performed after the first message is transmitted successfully.    -   The NAS layer sends the message 745 to the RRC layer.

The RRC builds the RRC connection setup complete message at operation1020. The RRC connection setup complete message includes the followinginformation.

-   -   Routing information for determining MME 125 to which the NAS        message has to be routed (selectedPLMN-Identity, registeredMME).    -   dedicatedInfoNAS (message 745)    -   Alternatively, if the short data transfer procedure is not        indicated in the RRC connection request message, the indication        is included in the message.    -   If the RRC connection setup complete message cannot be        transmitted in one MAC PDU, (i.e. if the message is segmented        and transmitted across a plurality of MAC PDUs), the UE 135        includes the following information in the MAC PDU carrying the        first part of the RRC connection setup complete message.    -   information indicating the residual size of the RRC connection        setup complete message (or buffer status report).    -   channel state-related information. This may be the RSRP        measurement result of the serving cell. This also may be the        information processed based on the RSRP like CQI. The eNB 105        allocates resource for transmitting RRC connection setup        complete message to the UE 135.

The UE 135 transmits the RRC connection setup complete message throughthe ARQ-protected SRB 1.

The UE 135 configures the message 750 for the data occurring on the sameEPS bearer and sends the message to the eNB 105 at operation 1025.

FIG. 11 shows the operations of the MME 125.

The MME 125 receives a NAS message addressed to a certain UE 135 atoperation 1105. The MME 125 checks whether the NAS message is themessage 745 or the message 750 at operation 1110. If the message is thefirst NAS message transmitted by the UE 135 in ECM-IDLE state and if themessage type filed includes the information indicating the message towhich data transfer procedure 2 is applied, this message is the message745. If the message is not the first NAS message transmitted by the UE135 in ECM-IDLE state but if the message type field including theinformation indicating the message to which the data transfer procedure2 is applied, this message is the message 750.

If the received message is neither the message 745 nor the message 750,the MME 125 performs integrity check on the received NAS message atoperation 1115 and, if the integrity is verified, performs subsequentoperation necessary.

If the received message is either the message 745 or the message 750,the UE 135 performs integrity check and deciphering on the receivedmessage at operation 1120 and, if the integrity check is successful,sends the IP packet included in the message to the S-GW 130 of the UE135 at operation 1125.

In the above embodiment, it is possible to modify the operation 520 ofFIG. 5 such that the UE 135 concatenates the two NAS messages fortransmission. That is, the UE 135 transmits the NAS message includingthe normal service request message and the IP packet to the eNB 105 atoperation 520, and the eNB 105 relays this message to the MME 125. If itis determined to use the data transfer procedure 2, the UE 135 generatesthe service request message according to the normal procedure andactivates the ciphering function of the security 1 immediately unlikethe normal procedure. The UE 135 generates a NAS message including theIP packet and applies ciphering to the NAS message. The NAS messageincluding the service request message and the IP packet may be includedin the RRC connection setup complete message. If the RRC connectionsetup complete message is received, the eNB 105 sends the MME 125 theNAS message including the service request message and the IP packet, andthe MME 125 performs integrity check on the service request message and,if the integrity is verified, determines the deciphering key byreferencing the KSI information. The MME 125 deciphers the NAS messageincluding the IP packet by applying the deciphering key. The MME 125extracts the IP packet from the NAS message and transmits the IP packetto the S-GW 130 of the UE 135.

FIG. 12 is a flowchart illustrating another modified security 1procedure-related operations.

In a modified security 1 procedure, the UE 135 generates a servicerequest message for transitioning to the EMM-CONNECTED state atoperation 1205. If the service request message is generated completely,the UE 135 activates (initiates) the ciphering function of the security1 at operation 1210. Next, the UE 135 generates the NAS messageincluding the IP packet (hereinafter, referred to IP NAS message) andapplies ciphering to the message at operation 1215. The service requestmessage and the IP NAS message are transmitted to the MME 125 atoperation 1220, and the MME 125 performs integrity check on the servicerequest message at operation 1225 and, if the message is verified,activates the ciphering function at operation 1230. The MME 125 performsdeciphering on the IP NAS message received along with the servicerequest message at operation 1235. The service request message maydiffer from the normal service request message and, herein, is referredto as service request type 2 message. If the service request message isreceived, the MME 125 performs the procedure for DRB setup and,otherwise if the service request type 2 message is received, does notperform the procedure. The service request type 2 message format has anextra message type field as compared to the normal service requestmessage.

FIG. 13 shows the operation of the UE 135 in the case that the modifieddata transfer procedure 2 is used.

If the aforementioned short data transfer procedure invoke condition isfulfilled, the UE 135 initiates the modified data transfer procedure 2at operation 1305.

The UE 135 transmits the RRC connection request message in the randomaccess procedure at operation 1310. The message indicates the reason ofthe RRC connection setup procedure. The UE 135 may inform that themessage is for the short data transfer procedure. The RRC connectioncomplete message may also indicate the required of the short datatransfer procedure.

If the RRC connection setup message is received, the UE 135 performsfollowing operations at operation 1315.

-   -   The UE establishes SRB 1 according to the information received        in the RRC connection setup message.    -   The UE notifies the higher layer of the short data transfer        capability (manages EPS bearer data transfer). Then the EPS        bearer management entity sends the NAS layer the IP packet.    -   The NAS layer generates the service request type 2 message and        the IP NAS message. The IP NAS message format is identical with        the message 750. The NAS layer applies the integrity protection        to the service request type 2 message and ciphers the IP NAS        message with the current NAS security key and other variables.    -   The NAS layer delivers the service type 2 message and the IP NAS        message to the RRC layer.

The RRC builds the RRC connection setup complete message at operation1320. The RRC connection setup complete message includes the followinginformation.

-   -   Routing information for determining MME 125 to which the eNB 105        routes the NAS message (selectedPLMN-Identity, registeredMME).    -   dedicatedInfoNAS1 as the service request type 2 message and        dedicatedInfoNAS2 as the IP NAS message.    -   Alternatively, if the short data transfer procedure is not        indicated by the RRC connection request message, it may be        indicated by this message.    -   If the RRC connection setup complete message cannot be        transmitted in one MAC PDU (i.e. the message is segmented to be        transmitted with a plurality of MAC PDUs), the UE 135 may        include the following information in the MAC PDU carrying the        first part of the RRC connection setup complete message.    -   Information indicating residual size of the RRC connection setup        complete message.    -   channel condition-related information. It may be the RSRP        measurement result of the serving cell. It may also be the        information processed based On RSRB like CQI. The eNB 105        allocates the resource for the RRC connection setup complete        message to the UE 135 based on this information.

The UE 135 sends the RRC connection setup complete message through theARQ-protected SRB 1.

The UE 135 configures the message 750 with the data occurring on thesame EPS bearer and sends the message to the eNB 105 at operation 1325.

FIG. 14 shows the mobile terminated call (mobile terminated case)operation.

The S-GW 130 has the information on the EPS bearer whether it is forshort data transfer procedure. The IP packet arrives at the S-GW 130. Ifthe IP packet is transmitted for the EPS bearer for the short datatransfer, the S-GW 130 sends the MME 125 the IP packet in the DL DATANOTIFICATION at operation 1405. The MME 125 stores the IP packet andperforms the paging procedure to the eNBs at operation 1410. The pagingmessage may include the indicator for indicating the message istransmitted for the short data transfer procedure. If the paging messageis received, the eNB 105 transmits the paging message through the airinterface.

When the paging message addressed to the UE 135 is received, the UE 135transmits the RRC connection request message through random accessprocedure at operation 1415. The eNB 105 transmits the RRC connectionsetup message at operation 1420. If the RRC connection setup message isreceived, the UE 135 establishes the SRB 1 and builds the servicerequest type 2 message. The UE 1350 multiplexes the service request type2 message with the RRC connection setup complete message and sends themultiplexed message through the SRB 1. If the RRC connection setupcomplete message is received, the eNB 105 determines a MME 125 to whichthe service request type 2 message is delivered. The eNB 105 generate anappropriate S1 message and includes the service request type 2 messagetherein. The eNB 105 sends the MME 125 the S1 message at operation 1430.The MME 125 performs integrity check. If the integrity check issuccessful, the eNB 105 ciphers the stored IP packet with the securitykey indicated by the KSI in the service request type 2 message. The MME125 generates an NAS IIP message. The MME 125 generates a DL DIRECTTRANSFER message including the IP packet at operation 1435 and sends themessage to the eNB 105 at operation 1435. The eNB 105 generates the DLDIRECT TRANSFER message including the NAS IP message and sends themessage to the UE 135. The UE 135 receives the NAS IP message includedin the DL DIRECT TRANSFER message. The NAS layer of the UE 135 deciphersthe NAS IP message and delivers the deciphered message to an appropriateentity (i.e. IP layer of the UE 135).

Embodiment 2

The embodiment 2 of the present disclosure proposes a method andapparatus for generating a special DRB in the RRC connection setupprocedure and transmitting IP packets through the specially DRB.

FIG. 15 is a flowchart illustrating a data transmission procedureaccording to the embodiment 2.

A data occurs on the EPS bearer established for use of the data transferprocedure 3 at operation 1500. The data transfer procedure 3 ischaracterized as follows.

-   -   Data transfer without security 2 establishment    -   Data transfer without DRB setup

The UE 135 generates an RRC connection request message and transmits themessage through random access procedure at operation 1505. The RRCconnection request message includes an indicator for indicating that themessage is generated for short data transfer procedure and a special DRBhas to be established in the RRC connection setup procedure.

If the RRC connection request message including the short data transferindicator, the eNB 105 performs following operations at operation 1510.

-   -   Perform Call Admission Control. If it is possible to admit the        request, the eNB 105 performs the following operations.        Otherwise, the eNB 105 rejects the RRC connection request.    -   Determine SRB1 configuration    -   Determine special DRB configuration. The special DRB includes a        PDCP entity and an RLC AM entity. The PDCP entity and RLC AM        entity configurations are determined in the way of satisfying        the QoS requirements for short data transfer (i.e. high        reliability and delay at low or intermediate level).    -   Establish SRB 1 and special DRB according to the determined        configuration.    -   Generate RRC connection setup message based on the SRB 1 and        special DRB configuration and transmit the RRC connection setup        message.

If the RRC connection setup message is received, the UE 135 performs thefollowing operations at operation 1515.

-   -   Establish SRB 1 and special DRB according to the received        configuration information    -   The RRC notifies the higher layer of availability of data        transmission    -   The higher layer sends the IP packet to the special DRB.    -   The special DRB processes the IP packet. Particularly, the        special DRB adds the following information to the IP packet.    -   Routing information (i.e. IP address) of the S-GW 130 to which        the IP packet has to be sent.    -   The above information may added by a predetermined protocol        entity of the special DRB. For example, the information may be        included in the PDCP header as shown in FIG. 16.    -   REL-8/9 PDCP header including PDCP serial number    -   The additional information 1605 is the routing information of        the related S-GW 130.    -   The security information 1610 may be added by other protocol        entity performing the ciphering.    -   The security information may include the information on the        variables such as COUNT and ciphering key.    -   Perform the operation necessary for transmitting the short data        through the special DRB. The necessary operation may include        requesting for scheduling and reporting the size of the short        data (including L2 header length as far as possible).    -   When uplink grant for new transmission is possible, the UE 135        transmits the short data through the special DRB.

If the short data is received through the special DRB, the eNB 105performs the following operations.

-   -   Determine the S-GW 130 to which the security protected short        data (hereinafter, referred SP short data) 1615 based on the        address of the S-GW 130 in the additional information.    -   Transmit the SP short data to the S-GW 130 through the common        S1-U bearer. There may be a plurality of S-GWs connected to the        eNB 105. The eNB 105 has at least one common S1-U bearer(s) for        each S-GW 130. The eNB 105 determines the S-GW 130 to which the        SP short data has to be transmitted based on the S-GW 130        address included in the additional information 1605.    -   When transmitting the SP short data through the common S1-U        bearer, the eNB 105 adds necessary information to the SP short        data such that the S-GW 130 is capable of identifying the UE 135        from which the SP short data is transmitted. This information        may be TMSI of the UE 135. The information also may be included        in the security information 1610 by the UE 135.

If the SP short data is received through the S1-U bearer, the S-GW 130performs following operations at operation 1525.

-   -   Check the UE identifier and deliver the SP short data to an        internal processor configured to process the SP short data in        the UE 135.    -   The processor deciphers the SP short data using the security        information added to the received SP short data.    -   After deciphering, the S-GW 130 routes the IP packet to the        destination.

FIG. 17 is a flowchart illustrating data transmission/receptionprocedure of the UE 135.

If the aforementioned short data transfer procedure invoke condition isfulfilled, the UE 135 initiates the modified data transfer procedure 3at operation 1705.

The UE 135 transmits the RRC connection request message through a randomaccess procedure at operation 1710. This message includes the reason ofthe RRC connection setup procedure. The UE 135 informs that the messageis transmitted for the short data transfer procedure.

If the RRC connection setup message is received, the UE 135 performs thefollowing operations at operation 1715.

-   -   The UE 135 establishes an SRB 1 according to the information        received in the RRC connection setup message.    -   The UE establishes a special DRB according to the information        received in the RRC connection setup message. The difference        between the special DRB and the normal DRB is that the special        DRB is established in the middle of the RRC connection        establishment procedure while the normal DRB is established in        the middle of the RRC connection reconfiguration procedure.    -   The UE notifies the higher layer of the availability of the        short data transfer (manages EPS bearer data transfer). The EPS        bearer management entity sends the IP packet to the special DRB.    -   The special DRB generates a PDCP SDU with the IP packet. The        additional information and security information are added to the        IP packet which is ciphered using the information included in        the security information.    -   The additional information include the routing information to        the related S-GW 130.

The UE 135 sends the PDCP SDU through the special DRB at operation 1720.From then on, the UE 135 transmits the IP packet of the EPS bearer usingthe special DRB.

FIG. 18 is a block diagram illustrating a configuration of the UE 135according to an embodiment of the present disclosure.

Referring to FIG. 18, the UE 135 according to an embodiment of thepresent disclosure includes a transceiver 1805, a controller 1810, amultiplexer/demultiplexer 1815, a control message processor 1830, higherlayer processors 1820 and 1825, an EPS bearer manager 1840, and a NASlayer device 1845.

The transceiver 180 receives data and predetermined control signalsthrough a downlink channel of the serving cell and transmits data andpredetermined control signals through an uplink channel. In the casethat multiple serving cells are configured, the transceiver 1805performs data and control signal transmission/reception through multipleserving cells.

The multiplexer/demultiplexer 1815 multiplexes the data generated by thehigher layer processors 1820 and 1825 and the control message processor1830 and demultiplexes the data received by the transceiver 1805 todeliver the demultiplexed data to appropriate higher layer processors1820 and 1825 and control message processor 1830.

The control message processor 1830 is an RRC layer device and takes anaction necessary for processing the control message received from theeNB 105. For example, if the RRC connection setup message is received,it establishes SRB1 and special DRB.

The higher layer processors 1820 and 1825 are DRB devices and may beformed per service. They process the data generated by the user servicessuch as File Transfer Protocol (FTP) and Voice over Internet Protocol(VoIP) and sends the processed data to the multiplexer/demultiplexer1815 or process the data from the multiplexer/demultiplexer 1815 andsends the processed data to the service applications of the higherlayer. One service may be mapped to one EPS bearer and one higher layerprocessor one by one. If a certain EPS bearer uses the data transferprocedure 2 or 3, no higher layer process is configured for thecorresponding EPS bearer.

The controller 1810 controls the transceiver 1805 and themultiplexer/demultiplexer 1815 to perform uplink transmission using anappropriate transmission resource at an appropriate timing by checkingthe scheduling command, e.g. uplink grant, received through thetransceiver 1805.

The EPS bearer manager 1840 determines whether to apply the datatransfer procedure 2 or 3 and, if it is determined to apply any of thedata transfer procedures, sends the IP packet to the RRC layer device orspecial DRB device.

FIG. 19 is a block diagram illustrating a configuration of the eNB 105,MME 125, and S-GW 130 according to an embodiment of the presentdisclosure, and the eNB 105 of FIG. 19 includes a transceiver 1905, acontroller 1910, a multiplexer/demultiplexer 1920, a control messageprocessor 1935, higher layer processors 1925 and 1930, a scheduler 1915,EPS bearer devices 1940 and 1945, and a NAS layer device 1950. The EPSbearer devices located at the S-GW 130, and the NAS layer device islocated at the MME 125.

The transceiver 1905 transmits data and predetermined control signalsthrough a downlink carrier and receives data and predetermined controlsignals through an uplink carrier. In the case that a plurality ofcarriers are configured, the transceiver 1905 may transmit and receiveddata and control signals through multiple carriers.

The multiplexer/demultiplexer 1920 multiplexes the data generated by thehigher layer processors 1925 and 1930 and the control message processor1935 and demultiplexes the data received by the transceiver 1905 todeliver the demultiplexed data to appropriate higher layer processors1925 and 1930, the control message processor 1935, and the controller1910. The control message processor 1935 processes the control messagetransmitted by the UE 135 to take a necessary action and generates thecontrol message addressed to the UE 135 to the lower layer.

The higher layer processors 1925 and 1930 may be configured for therespective EPS bearers and form the RLC PDUs with the data sent by theEPS bearer device and deliver the RLC PDUs to themultiplexer/demultiplexer 1920 and converts the RLC PDUs from themultiplexer/demultiplexer 1920 to the PDCP SDUs and delivers the PDCPSDUs to the EPS bearer device.

The scheduler allocates transmission resource to the UE 135 at apredetermined timing in consideration of the buffer status and thechannel state of the UE 135 and processes the signal received from theUE 135 and to be transmitted to the UE 135.

The EPS bearer device is configured per EPS bearer and processes thedata from the higher layer processes to transmit the processed data tothe next network node.

The higher layer processors and the EPS bearer devices are connected toeach other through S1-U bearer. The higher layer processor correspondingto the special DRB is connected to the EPS bearer for the special DRBthrough the common S1-U bearer.

The NAS layer device processes the IP packet included in the NAS messageand sends the IP packet to the S-GW 130.

What is claimed is:
 1. A method for transmitting data by a terminal in awireless communication system, the method comprising: identifyingwhether uplink data occurs or not; determining whether a terminal is inan idle state or not; and transmitting, to a base station, a messageassociated with a radio resource control (RRC) including a non-accessstratum (NAS) message, in case that the uplink data occurs and theterminal is in the idle state, wherein the NAS message includes theuplink data, and wherein the NAS message is integrity protected and theuplink data included in the NAS message is ciphered.
 2. The method ofclaim 1, wherein the idle state is a connection management idle(CM-IDLE) state.
 3. The method of claim 1, wherein the message is forconfirming a completion of an RRC procedure.
 4. The method of claim 1,wherein the message further comprises core network entity information,and wherein the core network entity information comprises routinginformation for determining a core network entity to which the basestation routes the NAS message.
 5. The method of claim 1, wherein themessage further includes information indicating that no further uplinkdata transmission is expected.
 6. The method of claim 1, wherein themessage is transmitted in case that a predefined condition is fulfilled.7. A terminal for transmitting data in a wireless communication system,the terminal comprising: a transceiver; and at least one processorcoupled with the transceiver and configured to: identify whether uplinkdata occurs or not, determine whether a terminal is in an idle state ornot, and transmit, to a base station, a message associated with a radioresource control (RRC) including a non-access stratum (NAS) message, incase that the uplink data occurs and the terminal is in the idle state,wherein the NAS message includes the uplink data, and wherein the NASmessage is integrity protected and the uplink data included in the NASmessage is ciphered.
 8. The terminal of claim 7, wherein the idle stateis a connection management idle (CM-IDLE) state.
 9. The terminal ofclaim 7, wherein the message is for confirming a completion of an RRCprocedure.
 10. The terminal of claim 7, wherein the message furthercomprises core network entity information, and wherein the core networkentity information comprises routing information for determining a corenetwork entity to which the base station routes the NAS message.
 11. Theterminal of claim 7, wherein the message further includes informationindicating that no further uplink data transmission is expected.
 12. Theterminal of claim 7, wherein the message is transmitted in case that apredefined condition is fulfilled.
 13. A method for receiving data by anetwork device in a wireless communication system, the methodcomprising: receiving, from a terminal, a message associated with aradio resource control (RRC) including a non-access stratum (NAS)message, in case that uplink data occurs and the terminal is in an idlestate, wherein the NAS message includes the uplink data; andtransmitting, to a core network entity, the NAS message including theuplink data, wherein the NAS message is integrity protected and theuplink data included in the NAS message is ciphered.
 14. The method ofclaim 13, wherein the idle state is a connection management idle(CM-IDLE) state.
 15. The method of claim 13, wherein the message is forconfirming a completion of an RRC procedure.
 16. The method of claim 13,wherein the message further comprises at least one of core networkentity information or information indicating that no further uplink datatransmission is expected.
 17. A network device for receiving data in awireless communication system, the network device comprising: atransceiver; and at least one processor coupled with the transceiver andconfigured to: receive, from a terminal, a message associated with aradio resource control (RRC) including a non-access stratum (NAS)message, in case that uplink data occurs and the terminal is in an idlestate, wherein the NAS message includes the uplink data, and transmit,to a core network entity, the NAS message including the uplink data,wherein the NAS message is integrity protected and the uplink dataincluded in the NAS message is ciphered.
 18. The network device of claim17, wherein the idle state is a connection management idle (CM-IDLE)state.
 19. The network device of claim 17, wherein the message is forconfirming a completion of an RRC procedure.
 20. The network device ofclaim 17, wherein the message further comprises at least one of corenetwork entity information or information indicating that no furtheruplink data transmission is expected.